JP4798873B2 - Fluidic elements, fluidic flow meters, and combined flow meters - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fluidic element manufacturing method, a fluidic element, a fluidic type flow meter, and a composite type flow meter, and more particularly, to manufacture a fluidic element that detects fluidic vibration corresponding to a change in fluid flow rate. The present invention relates to a method, a fluidic element, a fluidic flow meter, and a composite flow meter. For example, it can be used for a flow meter such as city gas (LNG) or provan gas (LPG), or a flow control device such as city gas (LNG), provan gas (LPG), an air conditioner, or an engine.
[0002]
[Prior art]
Conventionally, various proposals have been made for fluidic flow meters.
For example, a fluidic element 100 as shown in FIG. 4 is used as described in JP-A-8-210886. The fluidic element 100 includes a flow path formed by sequentially connecting a fluid inlet 101, a nozzle 102, a flow path expanding portion 103, and a fluid discharge port 104, and an outlet of the nozzle 102 disposed in the flow path expanding portion 103. , An end block 106 disposed on the downstream side thereof, and a return wall 107.
[0003]
In the fluidic flow meter using such a fluidic element 100, the fluid ejected from the nozzle 102 toward the downstream side is alternately distributed along the outside of the attracting element 105. Referring to a state in which the fluid flows below the attracting element 105 in FIG. 4, most of the fluid ejected from the nozzle 102 flows from the flow path expanding portion 103 toward the fluid discharge port 104, but a part thereof is the end block 106. Then, it becomes a return fluid along the return wall 107 on the lower side of the flow path expanding portion 103 and hits a jet of fluid newly ejected from the nozzle 102 from a right angle direction.
[0004]
Due to the energy of the return fluid, the jet of the fluid newly ejected from the nozzle 102 now flows to the upper side of the attracting element 105, and partly hits the end block 106 along the return wall 107 on the upper side of the flow path expanding portion 103. As a result, the fluid becomes a return fluid and hits the jet of fluid newly ejected from the nozzle 102 from a right angle direction.
[0005]
Due to the energy of the return fluid, a jet of fluid newly ejected from the nozzle now flows below the attracting element 105. The distribution of the flow of the jet ejected from the nozzle 102 is repeated in this way.
[0006]
A fluidic type flow meter detects the frequency of vibration (alternating pressure wave) generated in a fluid as described above by a pressure sensor, and converts the detected output into an electrical signal to measure the fluid flow rate. Is. In such a fluidic type flow meter, when the fluid is ejected from the nozzle 102 having a constant width toward the attracting element 105, a high-speed “jet” faster than the flow velocity of the surrounding fluid and The relationship with the “return flow” seen on the downstream side of the attracting pendulum 105 is important, and the shape of the attracting penetrator 105 plays an extremely important role in the fluidic vibration characteristics when considered in a two-dimensional field.
[0007]
More specifically, when the “jet flow” from the nozzle 102 is ejected into a semi-infinite space, the direction of the “jet flow” is stabilized, but the space of the flow path expanding portion 103 is limited, and the attracting element 105 is at the center. Therefore, it is considered that the direction of the initial velocity when the jet is ejected from the nozzle 103 cannot be maintained, so that the two-dimensional jet becomes unstable, and this instability causes the start of fluidic vibration.
[0008]
On the other hand, an asymmetrical vortex (Karman vortex) is generated on the downstream side of the attracting element 105 arranged in the flow, and this vortex row becomes a meandering flow. Therefore, it is considered that the “return flow” becomes an oscillating flow and cannot be stabilized. As described above, both the “jet flow” and the “return flow” are unstable due to the influence of the shape of the attracting element 105 and the wall surface of the end block 106 and the flow path expanding portion 103.
[0009]
[Problems to be solved by the invention]
Conventional fluidic type flowmeters are poor in linearity in the small flow range, but are suitable for measurement in the large flow range. For example, gas meters that measure the flow of city gas are suitable for measurement in the small flow range. A composite flow meter having a thermal flow detection sensor such as a flow sensor and a fluidic flow meter is used.
[0010]
For this reason, the fluidic type flow meter has a low minimum vibration flow rate (starting flow of fluidic vibration), and a wide dynamic range is desired for the flow rate range. If the fluid vibration start amount of the fluidic type flow meter can be used from 0 flow rate, a flow meter using only the fluidic type flow meter can be realized without using a thermal flow rate detection sensor. Even if this is not the case, if the flow rate at the start of stable fluid vibration of the fluidic flow meter can be reduced as much as possible, the required specifications for the thermal flow rate detection sensor can be relaxed.
[0011]
That is, in the current combined flow meter, for example, a full scale of 4000 L (liter) / h (hours) and a range of 200 L / h to several thousand L / h is handled by a fluidic flow meter, and a range of 0 to 200 L / h. Is handled by a thermal flow sensor. For this reason, there is a problem in that it is difficult to obtain measurement accuracy in a small flow rate region because the flow rate handling range of the thermal flow rate detection sensor is as many as two digits.
[0012]
As a result, strict specifications are required for the performance of the thermal flow rate detection sensor, and complicated signal processing and flow rate correction calculation processing are required when used as a flow meter. Therefore, even if the fluid vibration start amount of the fluidic type flow meter can be reduced to 100 L / h or less, the influence on improvement in terms of ease of signal processing, reliability, or manufacturing cost is increased. . For this reason, various experimental studies have been conducted on the flow rate (minimum vibration detection flow rate) and flow rate-frequency characteristics when vibration is started to be detected by a fluidic flow meter. It has been found to be an important regulator, and various proposals have been made so far.
[0013]
Specifically, it is desirable that the side wall or return wall of the flow path expanding portion is perpendicular to the bottom surface, and is preferably constant in the depth direction, and an optimum shape exists. So it has such a shape.
[0014]
If the side wall of the channel expansion part mentioned above, that is, the return wall is tilted inside the channel expansion part rather than perpendicular to the bottom surface, it is far away from the return flow, so Since energy is lost, the flow rate (Q) dependence of the fluidic vibration frequency (F) becomes lower at the same flow rate, and the linearity (dF / dQ) of the flow rate-vibration frequency becomes worse.
[0015]
On the other hand, when the side wall of the flow channel expanding portion, that is, the return wall is tilted to the outside of the flow channel expanding portion rather than perpendicular to the bottom surface, the fluidic vibration frequency (F) depends on the flow rate (Q). The vibration frequency at the same flow rate becomes higher, and the linearity (dF / dQ) of the flow rate-vibration frequency becomes worse.
[0016]
Therefore, if the perpendicularity to the bottom surface of the return wall is managed, there will be no problem in terms of performance.
[0017]
However, in the laboratory, the aluminum block was manufactured by cutting, so there was no problem. It has been found that making it perpendicular in the depth direction is a costly issue and not always easy. In other words, in the normal mold molding method, the return wall stands upright from the floor surface (bottom surface) of the fluidic element, so that thermal stress is applied due to the difference in temperature distribution between the floor surface during molding and the top of the return wall. If the end block is tilted with respect to the nozzle outlet or there is a burr at the lower end of the return wall, the flow state is disturbed between the part where the burr is present and the part where it is not, There was a problem that the performance as a flow meter was remarkably deteriorated.
[0018]
For this reason, when manufacturing by mold molding with emphasis on productivity, the return wall is rigid by forming a curved surface at the lower end of the return wall in order to prevent the return wall from tilting or generating burrs. It is necessary to make it. However, as the radius of the curved surface increases, the rigidity increases and the verticality improves, but the fluctuation of the separation position of the jet flow with respect to the lower end of the return wall increases, and as a result, the fluidic vibration frequency linearly with respect to the flow rate. There was a problem of worsening the nature.
[0019]
The present invention has been made in view of the above, and stabilizes the performance due to the optimum shape obtained in the laboratory even during production, the fluidic vibration, and the flow measurement region by the fluidic vibration output is a small flow region. The shape of the lower end of the return wall that can be molded while maintaining the spread to the side, that is, the manufacturing method of a fluidic element having a curved surface radius and a cut surface, and the fluidic element produced by the manufacturing method, fluidic element An object of the present invention is to provide a type flow meter and a composite type flow meter.
[0040]
[Means for Solving the Problems]
The fluidic element according to claim 1 is disposed in the flow passage expanding portion at a position facing a nozzle and a flow passage expanding portion wider than a cross-sectional area of the nozzle, and the outlet of the nozzle. And an end block arranged in the flow passage enlarged portion at a position downstream of the attractor, and the flow of the fluid ejected from the nozzle is distributed to the left and right around the attractor In the fluidic element that generates an alternating pressure wave, the lower end of the return wall corresponding to the inner wall of the flow passage expanding portion returns the fluid along the wall to stabilize the fluid evenly distributed by the attracting element. When the depth of the flow path enlarged portion is h and the radius of the lower end portion of the return wall is R, the radius of the lower end portion of the return wall is set to be smooth. R and the depth h of the flow path enlarged portion Relationship, characterized in that it is formed as a R / h = 0.12 or less curved.
[0041]
According to the first aspect of the present invention, the fluctuation of the fluid separation position at the lower end portion of the return wall is reduced and the position where the vortex is generated is stabilized, so the return of the return flow is stabilized.
[0049]
According to the first aspect of the present invention, since the radius of the curved surface is given specifically, the fluctuation of the fluid separation position at the lower end of the return wall of the fluid ejected from the nozzle is below a certain range. The return of the return flow is stabilized.
[0058]
A fluidic flow meter according to claim 2 is generated by the fluidic element according to claim 1 and the fluidic element that outputs a signal corresponding to an alternating pressure wave generated by the fluidic element. And a pressure sensor that outputs a signal corresponding to the alternating pressure wave.
[0059]
According to the second aspect of the present invention, since the fluid ejected from the slip is distributed by the attracting element, the fluctuation of the separation position of the fluid at the lower end of the return wall is reduced. The return can be stabilized.
[0060]
The composite flow meter according to claim 3, characterized in that it comprises a fluidic flow meter according, and a small flow rate range detection element for detecting the flow rate of the fluid of the small flow rate region, the to claim 2 And
[0061]
According to the third aspect of the present invention, after the fluid ejected from the nozzle is distributed by the attracting element, the fluctuation of the separation position of the fluid at the lower end of the return wall is reduced, and the return of the return flow is stabilized. A wide dynamic range of the measured flow rate can be obtained.
[0062]
According to a fourth aspect of the present invention, in the composite flow meter according to the third aspect , the small flow rate region detecting element is disposed on the inlet side of the nozzle of the fluidic type flow meter. To do.
[0063]
According to the fourth aspect of the invention, the same effect as that of the third aspect of the invention can be obtained, and the configuration of the flow path can be further simplified.
[0064]
According to a fifth aspect of the present invention, in the composite flow meter according to the fourth aspect , the small flow rate region detecting element is formed at a position that is not affected by fluctuations in the fluid flow by the nozzle of the fluidic flow meter. It arrange | positions in the made small flow volume flow path.
[0065]
According to the fifth aspect of the present invention, the same effect as that of the fourth aspect of the invention can be obtained, and when the flow rate of the fluid is measured by the output of the small flow rate detection element, Measurement can be performed without being influenced by fluctuations in the flow of fluid in the return wall.
[0066]
A sixth aspect of the present invention is the composite flow meter according to any one of the third to fifth aspects, wherein a thermal flow rate detection sensor is used as the small flow rate region detection element.
[0067]
According to the sixth aspect of the invention, the same effects as those of the third to fifth aspects of the invention can be obtained, and the measurement sensitivity in a small flow rate region can be increased.
[0068]
DETAILED DESCRIPTION OF THE INVENTION
Exemplary embodiments of a fluidic element manufacturing method, a fluidic element, a fluidic type flow meter, and a composite type flow meter according to the present invention will be described below in detail with reference to the accompanying drawings.
[0069]
FIG. 1 is a perspective view of a fluidic element according to the present embodiment, and FIG. 2 is a plan view showing a schematic structure of a composite flow meter according to the present embodiment. First, the configuration of the fluidic element 1A will be described with reference to FIG. The fluidic element 1A includes a flow passage restricting portion 2 having a flow passage cross-sectional area narrowed in the fluid flow direction indicated by an arrow in the drawing, a nozzle 3, and a flow passage wider than the cross-sectional area of the nozzle 3. At a position on the downstream side of the attracting element 7, a flow path 5 formed by sequentially connecting the expanding part 4, an attractor 7 disposed in the flow path expanding part 4 at a position facing the outlet 6 of the nozzle 3. It has an end block 8 disposed in the flow path expanding portion 4 and is molded using a plastic material so as to have a symmetrical shape across a center line passing through the center of the nozzle 3. The upstream end of the flow path narrowing section 2 and the downstream end of the flow path expanding section 4 are open.
A plurality of grooves 9 are formed on the wall surfaces on both sides of the flow restrictor 2.
[0070]
Such a fluidic element 1A is incorporated in a flow meter main body 10 as shown in FIG. 2, and the opening surface of the upper surface is covered with a lid (not shown) that closes the upper surface of the flow meter main body 10. A pressure sensor (not shown) is attached to the upper surface of the lid.
[0071]
This pressure sensor detects the alternating pressure wave of the fluidic element 1A through holes 11 arranged on both sides on the outlet 6 side of the nozzle 3 and formed in the lid, and outputs an electrical signal corresponding to the detected pressure. To do.
[0072]
Further, a rectifying network 12 and a rectifying grid 13 are incorporated in the groove 9 formed in the fluidic element 1A. The flow meter body 10 is formed with a fluid inlet 14, a fluid outlet 15, and a flow path 16 through which a gas as a fluid flows from the fluid inlet 14 toward the fluid outlet 15. A fluidic element 1A is arranged at the center of the substrate.
[0073]
The fluidic element 1 </ b> A has an upstream side of the flow path restricting portion 2 connected to the fluid inlet 14, and an outlet side of the flow path expanding portion 4 is connected to the fluid outlet 15. Furthermore, a shutoff valve 18 is assembled in the flow path 16 on the upstream side of the fluidic element 1A so that the drive section 17 shuts off the flow path 16 when subjected to abnormal vibration such as an earthquake. The fluidic flow meter 20 is configured by the above assembly.
[0074]
Further, a thermal flow rate detection sensor (hereinafter referred to as a flow sensor in this embodiment) 19 as a small flow rate detection element 19 is disposed on the inlet side of the nozzle 3 of the fluidic element 1A, thereby providing a combined flow rate. A total of 30 is configured. Since the flow sensor 19 outputs an electrical signal corresponding to the gas flow rate, the gas flow rate is measured based on the output.
[0075]
The fluidic element 1 </ b> A, which is a main component of the fluidic flow meter 20, is configured such that when the gas flowing in from the fluid inlet 14 is ejected downstream from the nozzle 3, the gas alternates along the outside of the attracting element 7. It is distributed to. Referring to FIG. 2, the gas flows from the upper side of the attracting element 7. Most of the gas ejected from the nozzle 3 flows from the flow passage expanding portion 4 toward the fluid outlet 15, but a part thereof is the end block 8. Then, it becomes a return fluid along the upper side wall of the flow path expanding portion 4 and hits a jet of gas newly ejected from the nozzle 3 from a substantially perpendicular direction. Due to the energy of the return fluid, the gas jet newly ejected from the nozzle 3 now flows below the attractor 7, partially hits the end block 8, and extends along the lower side wall of the flow path expanding portion 4. As a result, the fluid becomes a return fluid and collides with a jet of gas newly ejected from the nozzle 3 from a substantially perpendicular direction.
[0076]
Due to the energy of the return fluid, a jet of gas newly ejected from the nozzle 3 now flows on the upper side of the attractor 7. The distribution of the flow of the jet ejected from the nozzle 3 is repeated by such a Coanda effect. The fluid vibration (alternating pressure wave) generated in this way is detected by a pressure sensor, and the gas flow rate is measured by converting the period of the output into an electric signal and recognizing it.
[0077]
By the way, the fluidic element 1A is molded by a plastic material such as ABS (Alkyl Benzene Sulfonate), PBT (Poly Butyrene Terephthalate), PC (polycabonate), POM (Polyacetal resin), BMC (Bulk Molding Compound). In this case, in order to reduce the dimensional change after molding, the plastic material has different shrinkage ratios depending on the direction, but ABS, PBT, PC, etc. having an average shrinkage ratio as low as about 5/1000 is preferable.
[0078]
In addition, since the mold is used when the fluidic element 1A is molded, the return wall is inclined and burrs are likely to occur at the lower end of the return wall. If the return wall is tilted or burr is formed at the lower end of the return wall, as described above, the fluid is distributed by the nozzle 3 and flows along the end block, causing the flow of the return flow to be disturbed when returning. Become.
[0079]
Therefore, in order to avoid the occurrence of the inclination and the burr, a curved surface is formed at the lower end portion of the return wall. If the radius of the curved surface is too large, the fluctuation of the fluid separation position becomes large. In addition, it is extremely difficult to set the burrs and inclinations to a constant value by finishing or the like, and it is also a costly method.
[0080]
For this reason, the fluidic element 1A of the present embodiment is molded so as to satisfy a tolerance that the lower end portion of the return wall is a curved surface having a certain radius or less. Here, the constant radius is R / h = 0.12 or less, where h is the depth of the flow path enlarged portion and R is the radius. In particular, R / h = 0.04 is even better. Since the depth h of the channel expansion portion is 25 mm in this example, the former radius R is 3 mm and the latter radius R is 1 mm.
[0081]
Therefore, the lower end portion of the return wall of the fluidic element 1A manufactured by such a method is maintained in a curved surface state having a radius of 3 mm or less from an edge (right angle) without the curved surface R. In such a configuration, when the gas is ejected from the nozzle 3, the fluid distributed by the inducer 7 flows along the end block, and the return flow of the return flow is stable.
[0082]
Also, the tolerance is such that the entire bottom end portion of the return wall in the bottom surface parallel to the layer direction of the flow of fluid flowing from the nozzle 3 and flowing through the flow passage expanding portion is uniformly curved with a certain radius or less. By molding the fluidic element 1A as described above, the fluidic element 1A is maintained in an upright state in the height direction by a lower end portion (not shown) of the return wall of the molded fluidic element 1A. Therefore, the return flow is stabilized even in a two-dimensional field.
[0083]
Furthermore, the fluidic element 1A is molded so as to satisfy the tolerance that both sides of the lower end of the return wall, which are distributed by the center line passing through the center of the nozzle and the center of the attractor, are uniformly curved with a certain radius or less. By doing so, the return wall is maintained in an upright state. Therefore, the return flow due to the Coanda effect is performed very evenly.
[0084]
Here, the radius of the curved surface at the lower end of the return wall is R / h = 0.04 (radius 1 mm), R / h = 0.12 (radius 3 mm), R / h = 0.16 (radius 4 mm), R The experimental results when /h=0.2 (radius 5 mm) are shown in FIG.
[0085]
FIG. 3 is a graph showing the pulse number (vibration frequency) dependence of the variation in the vibration frequency in the present embodiment, with R / h described above as a parameter. It is known that the variation of this pulse cannot satisfy the instrumental difference by the measuring method unless it is about 1% or less. In order to measure the instantaneous flow rate accurately, 10 pulses (10 vibrations) (By the way, if it is 1 Hz vibration, it will be 6 seconds).
[0086]
When this is seen in the graph of FIG. 3, R / h = 0.12 is satisfied. As shown in the graph of FIG. 3, when R / h = 0.16, the dependence of the variation pulse number is 1.5% (at 10 pulses), and when R / h = 0.2, the dependence of the variation pulse number. Is 1.8% (at 10 pulses), indicating that the fluidic vibration with respect to the flow rate is unstable.
[0087]
On the other hand, it is stable at R / h = 0.12. This value is an improved value compared to the prior art. It was a value that falls within the range of 3% of instrumental error allowed by the measurement method in a small flow rate range of 200 L / h to 400 L / h or less.
[0088]
In the case of further improvement, the ratio R / h of the radius R of the lower end portion of the return wall and the depth of the flow path enlarged portion may be further reduced. That is, at R / h = 0.04, the variation value is even smaller than that at R / h = 0.12. This indicates that the flow rate dependence of the fluidic vibration frequency at R / h = 0.04 has a larger slope dF / dQ than that at R / h = 0.12 and the flow rate measurement accuracy is good. It shows that it becomes.
[0089]
So far, an embodiment has been described in which the lower end portion of the return wall is molded so as to satisfy a tolerance such that the curved surface R has a certain radius or less. The constant radius referred to here is an R / h ratio when the depth of the flow path enlarged portion is h and the radius is R.
[0090]
However, in the present embodiment, it has been found that the lower end portion of the return wall may be a cut surface C that is less than or equal to a certain level, and it is only necessary to satisfy the tolerance due to the C / h ratio. For comparison, when R / h = 0.04 (radius 1 mm) and C / h = 0.04 (cut surface 1 mm) were tested, a curvature R was added to the lower end portion of the return wall. It was found that the same effect can be obtained when the cut surface C is added.
[0091]
In the present embodiment, since the flow sensor 19 is arranged on the inlet side of the nozzle 3 of the fluidic element 1, the configuration of the flow path 16 as the composite flow meter 30 can be simplified.
[0097]
According to the sixth aspect of the present invention, when the depth of the flow path expanding portion is h and the radius of the lower end portion of the return wall is R, the radius R of the lower end portion of the return wall and the flow path expanded portion Since the fluidic element is molded so as to satisfy the tolerance that the curved surface is less than R / h = 0.04 in relation to the depth h, the fluid separation position at the lower end of the return wall is determined. The fluctuation can be further suppressed than in the case of claim 5.
[0102]
【The invention's effect】
According to the first aspect of the present invention, the fluctuation of the separation position of the fluid on the return wall is small, and the distribution of the return flow is stabilized, thereby stabilizing the fluidic vibration in the small flow rate region and the fluidic vibration output. The flow rate measurement area can be expanded to the small flow rate side.
[0106]
According to the first aspect of the present invention, the return flow in which the fluid ejected from the nozzle is distributed by the inducer suppresses the fluctuation of the separation position of the fluid at the lower end of the return wall below a certain range, and The direction can be stabilized.
[0111]
According to the second aspect of the present invention, after the fluid ejected from the nozzle is distributed by the attracting element, the fluctuation of the separation position of the fluid at the lower end of the return wall is reduced, and the return of the return flow is stabilized. The fluidic type flow meter which can be made can be provided.
[0112]
According to the third aspect of the present invention, it is possible to provide a composite flow meter in which the fluid ejected from the nozzle can reduce the fluctuation of the separation position of the fluid in the end block and stabilize the direction of the return flow.
[0113]
According to the invention described in claim 4, the same effect as that of the invention described in claim 3 can be obtained, and the configuration of the flow path can be simplified.
[0114]
According to the fifth aspect of the invention, in addition to the effect of the fourth aspect of the invention, when measuring the flow rate of the fluid by the output of the small flow rate detection element, it depends on the fluctuation of the fluid flow in the nozzle. Measurement is possible without any problems.
[0115]
According to the invention described in claim 6, the same effect as that of the invention described in claims 3 to 5 can be obtained, and the measurement sensitivity in a small flow rate region can be increased.
[Brief description of the drawings]
FIG. 1 is a perspective view of a fluidic element according to an embodiment.
FIG. 2 is a plan view showing a schematic structure of a composite flow meter according to the present embodiment.
FIG. 3 is a graph showing the dependence of the variation in vibration frequency in the present embodiment on the number of pulses using R / h as a parameter.
FIG. 4 is a plan view showing a schematic configuration of a conventional fluidic element.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1A Fluidic element 2 Flow path restricting part 3 Nozzle 4 Flow path expansion part 5 Flow path 6 Outlet 7 Guiding element 8 End block 9 Groove 10 Flow meter body 11 Hole 12 Rectification network 13 Rectification grid 14 Fluid inlet 15 Fluid outlet 16 Flow path 17 Drive unit 18 Shut-off valve 19 Thermal type flow rate detection sensor (flow sensor)
20 Fluidic flow meter 30 Combined flow meter

Claims (6)

A flow path formed by connecting a nozzle and a flow path enlargement portion wider than the cross-sectional area of the nozzle, an attractor disposed in the flow path enlargement portion at a position facing the outlet of the nozzle, and a downstream side of the attractor A fluidic element that generates an alternating pressure wave by distributing the flow of fluid ejected from the nozzle to the left and right around the attracting element. ,
Corresponding to the inner wall of the flow passage expanding portion, the lower end portion of the return wall along which the fluid returns along the wall is formed to be smooth so as to stably return the fluid evenly distributed by the attracting element. and,
When the depth of the flow path expanding portion is h and the radius of the lower end portion of the return wall is R, the relationship between the radius R of the lower end portion of the return wall and the depth h of the flow path expanded portion is A fluidic element characterized by being formed as a curved surface with R / h = 0.12 or less . A fluidic element according to claim 1 ;
A pressure sensor for outputting a signal corresponding to an alternating pressure wave generated by the fluidic element,
A fluidic type flow meter characterized by comprising: Fluidic type flow meter according to claim 2 ,
A small flow rate detection element for detecting the flow rate of the fluid in the small flow rate range,
A combined flow meter characterized by comprising: The composite flow meter according to claim 3 , wherein the small flow region detecting element is disposed on an inlet side of the nozzle of the fluidic flow meter. The small flow rate region detecting element, according to claim 4, characterized in that arranged on the small flow rate flow path formed in a position that is not affected by fluctuations in the flow of fluid by the nozzle of the fluidic flow meter Combined flow meter. The composite flow meter according to any one of claims 3 to 5 , wherein a thermal flow rate detection sensor is used as the small flow rate range detection element.

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